Most nerves are mixed, meaning they contain both motor and sensory neurons.

Based on their functions, the neurons in nerves divide the peripheral nervous system into somatic and autonomic nervous systems.

Somatic neurons carry signals that allow the CNS to consciously monitor the external environment and control body movements. In contrast, autonomic neurons carry signals that allow the CNS to subconsciously regulate the body’s internal environment and control the activity of the soft organs (viscera).